Abstract:
Indonesia is located on the copper-gold belt, making it one of the top 10 largest gold-producing countries in the world. This is due to the formation of magmatic pathways caused by the convection currents of magma, which push tectonic plates to create upthrust fault zones. Upthrust faults serve as weak zones through which hydrothermal fluids penetrate to reach the Earth's surface. This process forms alteration zones, where chemical reactions occur between hydrothermal solutions and surrounding rocks, resulting in the formation of mineralization pathways. Tujuh Bukit, as one of the largest gold deposits in Indonesia, was formed from medium to high-grade porphyry and epithermal sulfide ores.
This research aims to determine alteration zones based on the Corbet and Leach method in samples from the Tujuh Bukit area. The research methodology involves the collection of both secondary and primary data. Secondary data includes research findings by Harrison in 2018, geological maps, and rainfall data in the research area. Primary data includes analyses using X-Ray Diffraction (X-RD) and Mineralogical Analysis on samples tested at the PSDMBP Laboratory. The research findings indicate that the difference in
alteration zones influences the formation of gold ore, specifically the advanced argilic and argilic alteration zones. During the formation phase, the advanced argilic alteration zone exhibits higher temperatures and lower pH levels compared to the argilic zone. There are three samples that fall into the advanced argilic zone, as indicated by the presence of alunite resulting from the breakdown of silicates by sulfuric acid.
The quartz content also affects the pH and temperature during the alteration process. Meanwhile, one sample falls into the argilic alteration zone.
